1. Field of Invention
The present invention is directed to a method and apparatus for multiple band communication. In particular, the present invention is directed to a mobile communication device that can access multiple systems simultaneously.
2. Description of Related Art
Presently, the emergence of 3rd Generation and higher mobile wireless communications systems creates a need for mobile communications handsets capable of accessing multiple communications systems, for example GSM and WCDMA communications systems serving a common geographical area. The full exploitation of the services of multiple communication systems requires that multi-mode wireless mobile communications devices operate simultaneously on more than one communication system and transition efficiently between communication systems without significant performance degradation.
Unfortunately, present multi-mode and multi-band wireless communications are incapable of accessing more than one communication system simultaneously. For example, the continuous receive and transmit nature of CDMA communications leaves no time for monitoring other communication systems as required for multimode operation such as, for example, assessing hand-off candidates.
Compression of the transmission of downlink and uplink information in continuous receive and transmit communications systems can create time for monitoring other communication systems. During such compression, more data is transmitted over shorter time intervals to avoid a reduction in the data rate. Unfortunately, transmission compression requires more power, resulting in increased burdens on system capacity. Furthermore the software to implement this compression may require more resources from the processor and memory, adding complexity to the design and also decreasing talk time.
Also, any attempts at present multi-mode and multi-band wireless communications without compression require multiple antennas. Unfortunately, additional antennas increase the cost, size, and complexity of a portable communication device.
The various aspects, features and advantages of the present invention will become more fully apparent to those having ordinary skill in the art upon careful consideration of the following Detailed Description of the Invention with the accompanying drawings described below.